This invention relates to power transmission systems, and more particularly to a remote receiver for load control which responds to pulses injected onto and carried by the power lines.
Centralized load management systems for power transmission provide the utility company with a number of features among which is the ability to automatically switch loads at remote stations in the system. For example, through control of deferable loads the utility company can reduce peak kilowatt demands, through control of multiple register tariff meters can accomplish time-of-day metering, or through control of capacitor banks can accomplish power factor correction. Since the receivers are connected to the power lines for control of their associated loads it is convenient to transmit coded messages right on the power lines for detection by the receivers and response by those coded for the particular message. A receiver is known for operation in that kind of environment, namely the Model AIT152S manufactured by Enertec. That receiver is characterized by an operating cycle that uses a common start pulse and one of a plurality of operate pulses. All receivers respond to the start pulse to initiate a cycle whereas only the receivers coded for the particular operate pulse respond to that pulse. The system is limited in flexibility because the number of load conditions which can be received is only as great as the limited number of operate pulses in a message.